Public Class Form1

    '---------- Local variables ----------

    'List of pictures
    Dim lstPic As New List(Of Image)
    Dim stat_lstPic As New List(Of Integer) 'Status (Pausing->0, Moving->1)

    'Positions
    Dim m_x, m_y, m_os_x, m_os_y As Integer

    'Times
    Dim ti_cntdn As Double 'Countdown

    'Flags
    Dim admin_ctrl As Integer 'Admin mode (User can control ->1, can't ->0)
    Dim lastmdir As Integer, mdir As Integer 'Direction

    'Help texts
    Const hlp_1 As String = "(1) Press Any 'ARROW KEY' To Choose An Initial Direction." & vbNewLine & "(2) Press 'SPACE' To Begin/Reset." & vbNewLine & "(3) You May Press Any Arrow Keys To Change The Direction When Object Is Moving."

    '---------- Local objects ----------

    'Labels
    Dim label_indic As New Label


    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

        local_kc_dir(e.KeyCode)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        '--- Variables ---
        admin_ctrl = 1
        lastmdir = -1 : mdir = 3 'Right
        ti_cntdn = 0.5

        m_os_x = 25 'Offset (X Axis)
        m_os_y = 20 'Offset (Y Axis)

        '--- List of Images ---
        lstPic.Add(Image.FromFile("上001.bmp"))
        lstPic.Add(Image.FromFile("下001.bmp"))
        lstPic.Add(Image.FromFile("左001.bmp"))
        lstPic.Add(Image.FromFile("右001.bmp"))

        '--- Obj. ---

        'PictureBox1 - Status
        stat_lstPic.Add(0)

        'PictureBox1 - Image & Location
        local_renew_resetpic()

        'Label
        local_build_obj()

        '--- Sub ---
        local_change_pic()
        local_renew_indic(0, hlp_1)

    End Sub


    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If Timer1.Enabled = False Then Exit Sub

        Static ti_ct As Double

        'Bouncing
        If admin_ctrl = 0 Then
            ti_ct = ti_ct + (Timer1.Interval / 1000)
            If ti_ct = ti_cntdn Then
                ti_ct = 0
                local_switch_moving()
                Exit Sub
            End If
        End If

        'Offset
        m_x = m_x + Choose(mdir + 1, 0, 0, -m_os_x, m_os_x)
        m_y = m_y + Choose(mdir + 1, -m_os_y, m_os_y, 0, 0)

        'Renew position of PictureBox1
        PictureBox1.Location = New Point(m_x, m_y)

        'Check collision with form
        If local_check_colli(PictureBox1, Me) = 1 Then
            local_new_bounce()
            local_change_pic()
        End If


    End Sub



    Private Sub local_build_obj()

        '--- Label ---

        'label_indic
        label_indic.Parent = Me
        label_indic.Location = New Point(70, 60)
        label_indic.AutoSize = True

    End Sub

    Private Sub local_renew_indic(ByRef mode As Integer, ByVal s As String) 'Renew indicator
        label_indic.Text = s
        label_indic.Visible = Not CBool(mode)
    End Sub

    Private Sub local_kc_dir(ByRef kc As Integer)

        'Check Admin
        If admin_ctrl = 0 Then Exit Sub

        'Determine the key
        Select Case kc
            Case Keys.Up
                mdir = 0
            Case Keys.Down
                mdir = 1
            Case Keys.Left
                mdir = 2
            Case Keys.Right
                mdir = 3
            Case Keys.Space
                'Start moving object when SPACE has been pressed, stop moving when pressing again
                local_switch_moving()
        End Select

        'Change image of PictureBox1
        local_change_pic()

    End Sub

    Private Sub local_change_pic()

        If lastmdir = mdir Then Exit Sub

        'Change picture in PictureBox1
        PictureBox1.Image = lstPic(mdir)

        'Save last dir
        lastmdir = mdir

    End Sub

    Private Sub local_switch_moving()

        'Switch value
        stat_lstPic(0) = Not stat_lstPic(0)

        'Show/Hide indicator
        local_renew_indic(stat_lstPic(0), hlp_1)

        'Enable Timer1
        Timer1.Enabled = CBool(stat_lstPic(0))

        'Reset position
        If stat_lstPic(0) = 0 Then
            local_renew_resetpic()

        End If

    End Sub

    Private Function local_check_colli(ByRef obj_src As Object, ByVal obj_dst As Object) As Integer 'Simple verification

        local_check_colli = 0

        If obj_src.location.x <= 0 Or obj_src.location.x + obj_src.width >= obj_dst.width Then
            Return 1
        End If

        If obj_src.location.y <= 0 Or obj_src.location.y + obj_src.height >= obj_dst.height Then
            Return 1
        End If

    End Function

    Private Sub local_renew_resetpic()

        'PictureBox1 - Image & Position
        With PictureBox1
            local_change_pic()

            m_x = 390 : m_y = 180
            PictureBox1.Location = New Point(m_x, m_y)
        End With

        'Variables
        lastmdir = -1
        admin_ctrl = 1

    End Sub

    Private Sub local_new_bounce()

        'Disable admin
        admin_ctrl = 0

        'Turn opposite dir.
        mdir = Choose(mdir + 1, 1, 0, 3, 2)

    End Sub


End Class

Public Class Form1

    '---------- Local structures ----------

    'Positions
    Structure struc_pos
        Dim x, y As Integer 'Current position
        Dim ini_x, ini_y As Integer 'Initial position
        Dim ang As Single 'Current angle
        Dim vx, vy As Single 'Current velocity
        Dim ini_vx, ini_vy As Single 'Initial velocity
        Dim ini_v As Single 'Initial velocity
        Dim g As Single  'Gravity constant
    End Structure

    '---------- Local constants ----------

    'Initial positions
    Const user_ini_v As Single = 80
    Const user_ini_x As Integer = 390, user_ini_y As Integer = 180

    '---------- Local variables ---------- 

    'Graphics
    Dim g As System.Drawing.Graphics
    Dim dstRect, srcRect As Rectangle

    'List
    Dim listPic As New List(Of Image) 'List of picture
    Dim listAng As New List(Of Integer) 'List of angle

    'Collection
    Dim collRep As New Collection

    'Positions
    Dim pos As struc_pos

    'Flags 
    Dim stat_moving As Integer 'Status (Pausing->0, Moving->1) 
    Dim stat_ang, max_ang As Integer 'Angle
    Dim passedTime, multiTi As Single 'Time

    'Help texts 
    Const hlp_1 As String = "(1) 按 ""上"",""下"" 切換角度" & vbNewLine & "(2) 按 ""空白鍵"" 開始發射/停止" & vbNewLine & vbNewLine & "當物體碰撞到底下邊緣才會消失"


    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

        local_kc_dir(e.KeyCode)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Dim i As Integer

        '--- Variables --- 

        'Position
        With pos
            .g = 9.8
            .ini_v = user_ini_v
        End With

        'Status
        stat_moving = 0
        stat_ang = 3

        'Time
        multiTi = 15

        '--- List of Images --- 

        max_ang = -1
        For i = 30 To 90 Step 5
            listPic.Add(Image.FromFile("ghost_" & i & ".bmp"))
            listAng.Add(i)
            max_ang += 1
        Next

        '--- Obj. --- 

        'PictureBox1 
        local_renew_resetpic()
        PictureBox1.Visible = False

        'Timer1
        Timer1.Interval = 20

        '--- Sub --- 
        local_change_pic()

    End Sub

    Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint

        dstRect = Me.ClientRectangle
        srcRect = dstRect

        g = e.Graphics

        '--- Picture ---
        dstRect = New Rectangle(New Point(pos.x, pos.y), PictureBox1.Size)

        g.DrawImage(PictureBox1.Image, dstRect, srcRect, GraphicsUnit.Pixel)

        '--- Help text ---
        Dim tempFont As New Font("Arial", 12)

        If stat_moving = 0 Then
            g.DrawString(hlp_1, tempFont, Brushes.Black, New Point(60, 60))
        End If

        '--- Dispose ---
        e.Graphics.Dispose()

    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If Timer1.Enabled = False Then Exit Sub

        'Accumulate time
        passedTime = passedTime + (Timer1.Interval / 1000) * multiTi

        'Renew position of PictureBox1 
        local_renew_pospic()

        'Check collision with form 
        local_check_colli(New Rectangle(pos.x, pos.y, PictureBox1.Width, PictureBox1.Height), Me)

        If collfind(0) = 0 Then
            If collfind(4) = 1 Then
                local_start_moving()
            Else
                local_after_colli(collRep(1))
            End If
        End If

    End Sub



    Private Sub local_kc_dir(ByRef kc As Integer)

        Dim flagchange As Boolean = False

        'Determine the key 
        Select Case kc
            Case Keys.Up
                If stat_moving = 0 And (stat_ang < max_ang) Then stat_ang += 1 : flagchange = True
            Case Keys.Down
                If stat_moving = 0 And (stat_ang > 0) Then stat_ang -= 1 : flagchange = True
            Case Keys.Space     'Start moving object when SPACE has been pressed, stop moving when pressing again
                local_start_moving()
        End Select

        'Change image of PictureBox1 
        If flagchange Then local_change_pic()

    End Sub

    Private Sub local_change_pic()

        PictureBox1.Image = listPic(stat_ang)
        Me.Refresh()

    End Sub

    Private Sub local_start_moving()

        'Switch value 
        stat_moving = Not stat_moving


        'Calibrate positions
        local_clb_pos(0)

        'Enable Timer1 
        passedTime = 0
        Timer1.Enabled = CBool(stat_moving)

        'Reset position 
        If stat_moving = 0 Then
            local_renew_resetpic()
        End If

    End Sub

    Private Sub local_clb_pos(ByRef mode As Integer)

        '----- Formula -----
        'vx=vx
        'vy=vy-(g*t)

        'x=x0+(v0x*t)
        'y=y0+(v0y*t)-(1/2*g*t^2)
        '___________________

        With pos
            If mode = 0 Then 'Initial values
                .ang = math_degtorad(listAng(stat_ang))
                .ini_vx = .ini_v * Math.Cos(.ang) : .ini_vy = .ini_v * Math.Sin(.ang)
            Else
                .vx = .ini_vx
                .vy = .ini_vy - (.g * passedTime)
                .ang = Math.Atan(.vy / .vx)
                If .vx < 0 And .vy > 0 Then .ang = math_revang(0, .ang)
                If .vx < 0 And .vy < 0 Then .ang = .ang + Math.PI

                '--- Debug ---
                Me.Text = "ang=" & .ang * 180 / Math.PI & " vx=" & .vx & " vy=" & .vy & " Delta y=" & (.vy * passedTime) - (0.5 * .g * (passedTime ^ 2))
                '_____________

                .x = .ini_x + (.ini_vx * passedTime)
                .y = .ini_y + -((.ini_vy * passedTime) - (0.5 * .g * (passedTime ^ 2)))
            End If
        End With

    End Sub

    Private Sub local_check_colli(ByRef rect As Rectangle, ByVal obj_dst As Object)

        collRep.Clear()

        If rect.Y <= 0 Then collRep.Add(3) : Exit Sub
        If rect.Y + rect.Height >= obj_dst.height Then collRep.Add(4) : Exit Sub
        If rect.X <= 0 Then collRep.Add(1) : Exit Sub
        If rect.X + rect.Width >= obj_dst.width Then collRep.Add(2) : Exit Sub

        collRep.Add(0)

    End Sub

    Private Sub local_renew_resetpic()

        'PictureBox1 
        With PictureBox1
            local_change_pic()

            pos.ini_x = user_ini_x : pos.ini_y = user_ini_y : pos.ini_v = user_ini_v

            pos.x = pos.ini_x : pos.y = pos.ini_y

            Me.Refresh()
        End With

    End Sub

    Private Sub local_renew_pospic()

        'Recalibrate positions
        local_clb_pos(1)

        'Renew position of picture
        Me.Refresh()

    End Sub

    Private Sub local_after_colli(ByRef mode As Integer)

        passedTime = 0

        With pos
            'Reset position & velocity
            .ini_x = .x : .ini_y = .y
            .ini_v = Math.Sqrt(.vx ^ 2 + .vy ^ 2)

            'Reverse angle
            .ang = math_revang(Fix((mode - 1) / 2), .ang)

            'Reset initial velocity (vx & vy)
            .ini_vx = .ini_v * Math.Cos(.ang) : .ini_vy = .ini_v * Math.Sin(.ang)

            'Force reversing direction of velocity
            Select Case mode
                Case 1
                    If .ini_vx < 0 Then .ini_vx = -.ini_vx
                Case 2
                    If .ini_vx > 0 Then .ini_vx = -.ini_vx
                Case 3
                    If .ini_vy > 0 Then .ini_vy = -.ini_vy
                Case 4
                    If .ini_vy < 0 Then .ini_vy = -.ini_vy
            End Select

        End With

    End Sub



    Private Function math_degtorad(ByRef deg As Single) As Single
        Return deg * Math.PI / 180
    End Function

    Private Function math_revang(ByRef mode As Integer, ByRef ang As Single) As Single

        'mode=0 -> By Y Axis
        'mode=1 -> By X Axis

        If mode = 0 Then
            Return Math.PI - (ang Mod Math.PI) + Fix(ang / Math.PI) * Math.PI
        Else
            Return (Math.PI * 2) - ang
        End If

    End Function

    Public Function collfind(ByRef f As Integer)

        Dim l As Long

        collfind = 0
        For l = 1 To collRep.Count
            If collRep(l) = f Then Return 1
        Next

    End Function

End Class

Public Class Form1

    '---------- Local structures ----------

    'Positions [位置的變數]
    Structure struc_pos
        Dim x, y As Integer 'Current position [目前的 x,y]
        Dim ini_x, ini_y As Integer 'Initial position [拋物線參考的最初 x,y，就是物理中表示的 x0,y0]
        Dim ang As Single 'Current angle [目前的角度，為碰撞時可轉換]
        Dim vx, vy As Single 'Current velocity [目前的速度分量]
        Dim ini_vx, ini_vy As Single 'Initial velocity [一開始的 速度分量，就是物理中表示的 vx0,vy0]
        Dim ini_v As Single 'Initial velocity [一開始的速度]
        Dim g As Single  'Gravity constant [重力常數]
    End Structure

    '---------- Local constants ----------

    'Initial positions
    Const user_ini_v As Single = 80 '[設定一開始的速度(可調整)]
    Const user_ini_x As Integer = 390, user_ini_y As Integer = 180 '[圖片一開始的座標(可調整)]

    '---------- Local variables ----------

    'Graphics [繪圖]
    Dim g As System.Drawing.Graphics
    Dim dstRect, srcRect As Rectangle

    'List [清單]
    Dim listPic As New List(Of Image) 'List of picture
    Dim listAng As New List(Of Integer) 'List of angle

    'Collection [集合]
    Dim collRep As New Collection

    'Positions [宣告座標的巢狀結構]
    Dim pos As struc_pos

    'Flags [旗標]
    Dim stat_moving As Integer 'Status (Pausing->0, Moving->1) [紀錄是否在移動]
    Dim stat_ang, max_ang As Integer 'Angle [角度(DEG)，與最大值]
    Dim passedTime, multiTi As Single 'Time [已經過時間，與時間加倍量]

    'Help texts
    Const hlp_1 As String = "(1) 按 ""上"",""下"" 切換角度" & vbNewLine & "(2) 按 ""空白鍵"" 開始發射/停止" & vbNewLine & vbNewLine & "當物體碰撞到底下邊緣才會消失"


    Private Sub Form1_KeyDown(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs) Handles Me.KeyDown

        local_kc_dir(e.KeyCode)

    End Sub

    Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        Dim i As Integer

        '--- Variables ---

        'Position
        With pos
            .g = 9.8
            .ini_v = user_ini_v
        End With

        'Status
        stat_moving = 0
        stat_ang = 3 '[設定一開始是第三張圖片，30度的]

        'Time
        multiTi = 15 '[時間加倍量，太低圖片會跑很慢]

        '--- List of Images ---
        '[讀取圖片，並讀取角度值]
        max_ang = -1
        For i = 30 To 90 Step 5
            listPic.Add(Image.FromFile("ghost_" & i & ".bmp"))
            listAng.Add(i)
            max_ang += 1
        Next

        '--- Obj. ---

        'PictureBox1
        local_renew_resetpic()
        PictureBox1.Visible = False

        'Timer1
        Timer1.Interval = 20

        '--- Sub ---
        local_change_pic()

    End Sub

    Private Sub Form1_Paint(ByVal sender As System.Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles MyBase.Paint

        dstRect = Me.ClientRectangle
        srcRect = dstRect

        g = e.Graphics

        '--- Picture ---
        dstRect = New Rectangle(New Point(pos.x, pos.y), PictureBox1.Size)

        g.DrawImage(PictureBox1.Image, dstRect, srcRect, GraphicsUnit.Pixel)

        '--- Help text ---
        Dim tempFont As New Font("Arial", 12)

        If stat_moving = 0 Then
            g.DrawString(hlp_1, tempFont, Brushes.Black, New Point(60, 60))
        End If

        '--- Dispose ---
        e.Graphics.Dispose()

    End Sub

    Private Sub Timer1_Tick(ByVal sender As Object, ByVal e As System.EventArgs) Handles Timer1.Tick
        If Timer1.Enabled = False Then Exit Sub

        'Accumulate time [時間累積]
        passedTime = passedTime + (Timer1.Interval / 1000) * multiTi

        'Renew position of PictureBox1 [更新圖片座標]
        local_renew_pospic()

        'Check collision with form [檢查是否碰撞]
        local_check_colli(New Rectangle(pos.x, pos.y, PictureBox1.Width, PictureBox1.Height), Me)

        If collfind(0) = 0 Then '[假如碰撞，這是呼叫 collfind 去找 collRep 中元素是否沒有 0 這個值，也就是函數檢查中檢查到碰撞]
            If collfind(4) = 1 Then '[底下的碰撞，再呼叫 local_start_moving 即可停止]
                local_start_moving()
            Else
                local_after_colli(collRep(1)) '[其他上、左、右邊的碰撞，轉換座標、速度、角度的函數，為了碰撞後接下來的反彈而作]
            End If
        End If

    End Sub



    Private Sub local_kc_dir(ByRef kc As Integer)

        Dim flagchange As Boolean = False

        'Determine the key
        Select Case kc
            Case Keys.Up
                If stat_moving = 0 And (stat_ang < max_ang) Then stat_ang += 1 : flagchange = True
            Case Keys.Down
                If stat_moving = 0 And (stat_ang > 0) Then stat_ang -= 1 : flagchange = True
            Case Keys.Space     'Start moving object when SPACE has been pressed, stop moving when pressing again
                local_start_moving()
        End Select

        'Change image of PictureBox1
        If flagchange Then local_change_pic()

    End Sub

    Private Sub local_change_pic()

        PictureBox1.Image = listPic(stat_ang)
        Me.Refresh()

    End Sub

    Private Sub local_start_moving()

        'Switch value
        stat_moving = Not stat_moving


        'Calibrate positions [調整座標]
        local_clb_pos(0)

        'Enable Timer1
        passedTime = 0
        Timer1.Enabled = CBool(stat_moving)

        'Reset position
        If stat_moving = 0 Then
            local_renew_resetpic()
        End If

    End Sub

    Private Sub local_clb_pos(ByRef mode As Integer)

        '----- Formula ----- [物理公式參考]
        'vx=vx
        'vy=vy-(g*t)

        'x=x0+(v0x*t)
        'y=y0+(v0y*t)-(1/2*g*t^2)
        '___________________

        With pos
            If mode = 0 Then 'Initial values
                .ang = math_degtorad(listAng(stat_ang)) '[把角度 DEG格式 轉換到 RAD格式]
                .ini_vx = .ini_v * Math.Cos(.ang) : .ini_vy = .ini_v * Math.Sin(.ang) '[設定 vx0,vy0 好讓接下來移動中公式使用]
            Else
                .vx = .ini_vx '[斜向拋射中 vx 不會變]
                .vy = .ini_vy - (.g * passedTime) '[斜向拋射 vy=vy0-(gt)]
                .ang = Math.Atan(.vy / .vx) '[用 ArcTan() 來更新角度的值]
                If .vx < 0 And .vy > 0 Then .ang = math_revang(0, .ang) '[底下這兩行是為了修正 ArcTan 的結果]
                If .vx < 0 And .vy < 0 Then .ang = .ang + Math.PI

                '--- Debug ---
                Me.Text = "ang=" & .ang * 180 / Math.PI & " vx=" & .vx & " vy=" & .vy & " Delta y=" & (.vy * passedTime) - (0.5 * .g * (passedTime ^ 2))
                '_____________

                .x = .ini_x + (.ini_vx * passedTime) '[底下兩行是更新目前座標 x,y]
                .y = .ini_y + -((.ini_vy * passedTime) - (0.5 * .g * (passedTime ^ 2)))
            End If
        End With

    End Sub

    Private Sub local_check_colli(ByRef rect As Rectangle, ByVal obj_dst As Object)

        collRep.Clear()

        If rect.Y <= 0 Then collRep.Add(3) : Exit Sub '[與天花板碰撞]
        If rect.Y + rect.Height >= obj_dst.height Then collRep.Add(4) : Exit Sub '[與地板碰撞]
        If rect.X <= 0 Then collRep.Add(1) : Exit Sub '[與左邊碰撞]
        If rect.X + rect.Width >= obj_dst.width Then collRep.Add(2) : Exit Sub '[與右邊碰撞]

        collRep.Add(0)

    End Sub

    Private Sub local_renew_resetpic()

        'PictureBox1
        With PictureBox1
            local_change_pic()

            pos.ini_x = user_ini_x : pos.ini_y = user_ini_y : pos.ini_v = user_ini_v

            pos.x = pos.ini_x : pos.y = pos.ini_y

            Me.Refresh()
        End With

    End Sub

    Private Sub local_renew_pospic()

        'Recalibrate positions [重新調整座標]
        local_clb_pos(1)

        'Renew position of picture [將觸發 Form1_Paint]
        Me.Refresh()

    End Sub

    Private Sub local_after_colli(ByRef mode As Integer)

        passedTime = 0

        With pos
            'Reset position & velocity [將目前的 x,y 載入到 x0,y0 等於是下次的拋物線從碰撞的地方開始]
            .ini_x = .x : .ini_y = .y
            .ini_v = Math.Sqrt(.vx ^ 2 + .vy ^ 2)

            'Reverse angle [轉換角度]
            .ang = math_revang(Fix((mode - 1) / 2), .ang)

            'Reset initial velocity (vx & vy) [利用轉換而來的角度來取得 vx0,vy0]
            .ini_vx = .ini_v * Math.Cos(.ang) : .ini_vy = .ini_v * Math.Sin(.ang)

            'Force reversing direction of velocity [有時邊緣的碰撞會造成連續碰撞，為了修正，而強制偵測並強制轉換 vx0,vy0]
            Select Case mode
                Case 1
                    If .ini_vx < 0 Then .ini_vx = -.ini_vx
                Case 2
                    If .ini_vx > 0 Then .ini_vx = -.ini_vx
                Case 3
                    If .ini_vy > 0 Then .ini_vy = -.ini_vy
                Case 4
                    If .ini_vy < 0 Then .ini_vy = -.ini_vy
            End Select

        End With

    End Sub



    Private Function math_degtorad(ByRef deg As Single) As Single
        Return deg * Math.PI / 180 '[Rad = Deg * pi / 180]
    End Function

    Private Function math_revang(ByRef mode As Integer, ByRef ang As Single) As Single

        'mode=0 -> By Y Axis [Y軸反射，例如 30度(DEG) 會轉成 150度(DEG)]
        'mode=1 -> By X Axis [X軸反射，例如 30度(DEG) 會轉成 330度(DEG)，不過這裡是 RAD 的轉換]

        If mode = 0 Then
            Return Math.PI - (ang Mod Math.PI) + Fix(ang / Math.PI) * Math.PI
        Else
            Return (Math.PI * 2) - ang
        End If

    End Function

    Public Function collfind(ByRef f As Integer) '[在 collRep 集合中尋找元素]

        Dim l As Long

        collfind = 0
        For l = 1 To collRep.Count
            If collRep(l) = f Then Return 1
        Next

    End Function

End Class